The present invention relates to a headlamp for a motor vehicle having an inclination detector for detecting whether or not the angle of irradiation of the headlamp is correct in a horizontal plane, and more particularly to a vehicular headlamp in which, when the angle of irradiation is not correct, it can be adjusted with ease.
An example of a vehicular headlamp aiming mechanism is disclosed, for instance, in coassigned U.S. patent application Ser. No. 07/370,949. A conventional aiming mechanism of this type will be described with reference to a movable reflector type headlamp.
As shown in FIG. 8, a reflector 2 is supported on a lamp body 1 at three points, namely, at one pivot point 3 fixed to the lamp body, and two aiming points 6 and 7 which correspond to two aiming screws 4 and 5 coupled to the lamp body. The one pivot point 3 and the two aiming points 6 and 7 are positioned in such a manner that the horizontal axis Lx connecting the horizontal aiming point 6 and the pivot point 3 and the vertical axis Ly connecting the vertical aiming point 7 and the pivot point 3 are perpendicular to each other as viewed from front. That is, the pivot point 3 is at the vertex of the angle subtending the oblique side (hypotenuse) of a right triangle. By turning the aiming screws 4 and 5, the distances of the aiming points 6 and 7 from the lamp body 1 are changed so that the reflector 2 is swung about the horizontal axis Lx and the vertical axis Ly, that is, the axis of irradiation of the headlamp is swung both in a horizontal plane and in a vertical plane.
Between the lamp body 1 and the reflector 2 is provided an inclination detector 8. The inclination detector 8 is positioned so that it does not adversely affect the effective reflecting surface of the reflector 2 and so that reading of the scale of the inclination detector is not adversely affected, even when the reflector 2 pivots about the horizontal axis Lx. In addition, in order to read the scale of the inclination detector 8 with ease, the latter is positioned inside the aiming point 6 in the horizontal plane including the horizontal axis Lx.
Sometimes the vertical axis Ly may not be parallel to the vertical line. In this case, the pivot point and the aiming points do not define a right triangle; however, the pivot point is at the vertex of the angle subtending the oblique side of the triangle.
Moreover, sometimes it is impossible to place the pivot point 3 at the vertex of the angle subtending the oblique side of the right triangle because of the configuration of the lamp body 1 or the reflector. Hence, with the above-described conventional three-point arrangement, the lamp body is unavoidably bulky, and accordingly the headlamp is unavoidably bulky.
The inventor has conducted intensive research on the above problem and found that the inclination of the reflector in the horizontal plane can be properly adjusted even when the pivot point is placed at other than the vertex of the angle subtending the oblique side of the right triangle defined by the pivot point and the aiming points. The invention is based on this finding.